Messages in this thread | | | Date | Sun, 27 Aug 2023 12:44:04 +0100 | From | Conor Dooley <> | Subject | Re: [PATCH v2] riscv: Only consider swbp/ss handlers for correct privileged mode |
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On Sun, Aug 27, 2023 at 01:40:03PM +0200, Björn Töpel wrote: > From: Björn Töpel <bjorn@rivosinc.com> > > RISC-V software breakpoint trap handlers are used for {k,u}probes. > > When trapping from kernelmode, only the kernelmode handlers should be > considered. Vice versa, only usermode handlers for usermode > traps. This is not the case on RISC-V, which can trigger a bug if a > userspace process uses uprobes, and a WARN() is triggered from > kernelmode (which is implemented via {c.,}ebreak). > > The kernel will trap on the kernelmode {c.,}ebreak, look for uprobes > handlers, realize incorrectly that uprobes need to be handled, and > exit the trap handler early. The trap returns to re-executing the > {c.,}ebreak, and enter an infinite trap-loop. > > The issue was found running the BPF selftest [1]. > > Fix this issue by only considering the swbp/ss handlers for > kernel/usermode respectively. Also, move CONFIG ifdeffery from traps.c > to the asm/{k,u}probes.h headers. > > Note that linux/uprobes.h only include asm/uprobes.h if CONFIG_UPROBES > is defined, which is why asm/uprobes.h needs to be unconditionally > included in traps.c > > Link: https://lore.kernel.org/linux-riscv/87v8d19aun.fsf@all.your.base.are.belong.to.us/ # [1]
> Reported-by: kernel test robot <lkp@intel.com> > Closes: https://lore.kernel.org/oe-kbuild-all/202308271841.HlnnHFL7-lkp@intel.com/
Delete these, LKP did not report the probes issue. The LKP bot says: > If you fix the issue in a separate patch/commit (i.e. not just a new version of > the same patch/commit), kindly add following tags
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